The present invention relates to an athletic shoe midsole design and construction. More particularly, the invention relates to a midsole assembly, which is comprised of a midsole formed of soft elastic material and a corrugated sheet disposed in the midsole.
The sole of an athletic shoe used in various sports is generally comprised of a midsole and an outsole, which is fitted under the midsole and directly contacts with the ground. The midsole is typically formed of soft elastic material in order to ensure adequate cushioning properties.
Generally, running stability as well as adequate cushioning properties are required in athletic shoes. There is a need to prevent shoes from being deformed excessively in the lateral or transverse direction when contacting the ground.
As shown in Japanese Utility Model Examined Publication No. 61-6804, the applicant of the present invention proposes a midsole assembly having a corrugated sheet therein, which can prevent such an excessive lateral deformation of shoes.
The midsole assembly shown in the above publication incorporates a corrugated sheet in a heel portion of a midsole and it can produce resistant force preventing the heel portion of a midsole from being deformed laterally or transversely when a shoe contacts with the ground. Thus, the transverse deformation of the heel portion of a shoe is prevented.
In such a way, by inserting a corrugated sheet into a midsole, the heel portion of a midsole tends to be less deformed in the transverse direction. When the corrugated sheet is formed especially of higher elastic material, that is, material having a higher modulus of elasticity, the heel portion of a midsole tends to be less deformed in the vertical direction as well. Therefore, by inserting a corrugated sheet, the heel portion of a midsole, where adequate cushioning properties are required, may undesirably show less cushioning properties in contacting the ground.
On the other hand, when a relatively lower elasticity material, that is, material having a lower modulus of elasticity, is used as a corrugated sheet, cushioning properties can be achieved to some degree at the time of contacting with the ground. In athletics such as tennis or basketball, however, where players move more often in the transverse direction, the transverse deformation of the heel portion of the shoes cannot be adequately restrained and running stability cannot be fully secured.
The object of the present invention is to provide a midsole assembly for an athletic shoe which can secure cushioning properties as well as the running stability.